Plasticizing rubber



Patented Oct. 11, 1938 du Pont de Nemours a company, .Wilmington, Del, acorporationotDela 1 ."No Drawing. Application August 1935. 7 Serial Nassau I p as Claims. (01. 18-50) This invention relates to the manufacture of rubber articles and more particularly to methods of treating rubber to produce a more plastic product.

,5 It is well known that rubber, when subjected to mechanical working, such as is obtained by the use of a rubber mill, and especially in the presence of oxygen. is rendered much' more plastic. 'I'he degree of plasticizing is determined to a great .10 extent by the temperature and time of milling.

When milled for a sufllcient length of time, rubber will become verysoft and at the same time will lose much of its ability to vulcanize. In order to reduce the time of milling andtoprevent the 15 deteriorating action of continued milling, it is common practice to add to the rubber, during the milling operation, certain materials which assist in producing softness.

The materials which are commonly used are 20 oils, esters, waxes, fats, alcohols, acids, resins, etc., which assist the production of soft rubber either by a swelling action on the rubber or by acting as a lubricant. Some of the more common softeners are mineral oil, pine tar, palm oi1,rosin oil, dl-,

5 butyl phthalate, paraflin', glycerine,laury1 alcohol and stearlc acid. It is also known that certain chemicals, such as diphenyl guanidine, have a slight softening action on the rubber while other products, such as benzidine, have a considerable stiffening action. a g

Rubber which hasbeensubiected to the action of swelling agents, such as mineral oil, kerosene and similar materials, is softened merely by the dlstending action of the swelling materials and the 35 degree of softening and swelling can be increased until the rubber assumes the consistency of a soft jelly or. cement. When such rubber is compounded with the usual vulcanizing agents and vulcanized, the swelling action of the softener 40 still persists and the vulcanized rubber has a low modulus'of elasticity and is inferior for many purposes. I 1

Rubber is probably composed of micelles which in turn consist of a larger number of molecules. 45 The softness or plasticity of the rubber islargely determined by the state of gelation and size 01 themicelles. Any reduction in the degree of association of the micelles or any means which will reduce the size of the micelle will result ina 50' softening action. Such peptizing actions are shown by accelerators, such diphenyl g'uanidine, although the effect is-almost entirely destroyed during vulcanization." An object of the present invention is to provide a class of materials which, when added to rubber in small amounts, will have agreater plasticizing action than those previously employed. A further object is to supply a class of materials which cause softening when used in relatively small amounts and without producing a material swelling action 10 on the rubber. A still further object is to supply a class of plasticizers for rubber, the eil'ect of which is largely destroyed during vulcanization. Another object isto supply a method of softening 1 rubber by means other than mechanical. Other objects are to provide new compositions of matter and .to advance the-art. Still other objects will appear hereinafter.

These objectsmay be accomplished in accord 'ance with our invention which comprises 3 ticizing unvulcanized rubber/by subjectingthe rubber to the action of;a small amount of a com-Z plex organic compound which is a chemical addition product of a metal salt and an unsymmetrically substituted hydrazine for a s'ufllcient'length 5 of time to produce a substantial increase in the plasticity ofthe rubber. .The rubber is subsequently shaped into the desired form and, if desired, vulcanized. i

By the term chemical addition product we mean the product formed by causing the metal salts to react upon the hydrazine chemically so that the metal salt is added on to the hydrazine to form a complex salt or compound but without destroying the fundamental structure of the hy- .35 draz'ine. These products are somewhat similar to quaternary ammonium compounds;

These compounds of our invention apparently reduce the degree of association of the micelles in the rubber or reduce the size of the micelles to 40 a much greater extent than any other compounds heretofore known for this purpose. The change,- in the state of the rubber gelinduced by our compounds, is not instantaneous but requires more or less time to develop. While a small immediate eifect may result, it is, in general, not great enough to be noticeable. However, upon standing for a period of time, the rubber, containing our compounds, becomes softened and continues'to become softened until the effect is sufficient to be easily detectable by hand testing methods. This softening effect continues at a decreasing rate until an apparent equilibrium condition is reached, after which little or no further softening takes place. The length of time required to reach this equilibrium varies considerably for different compounds and. decreases rapidly as the temperature isincreased. A beneficial softening action will in general be'noticed in periods of time which may vary from 15 minutes to two days. Also, the amount of softening, which willbe obtained over a given period of-time, will vary with the amount of plasticizing agent which is employed. However, the increase in softening effect of increased amounts of agent is not in proportion to the amount of agent added. The amount of agent to be added may be varied within an extremely wide range, depending upon the rubber, the other compounding ingredients and the desire of the user. However, for economical reasons, it will generally be found that from .1 to about 5% of the agent will be suiilcient for most p rposes. Also, the amount of softener'required will be reduced if the rubber is held at an elevated temperature after treatment.

The metal salts may be the salts formed from any metal and any acid reacting material which metal salt will form addition products with the hydrazines and without destroying such hydrazine. In general, the salts of the metals from lithium to lead in the electromotive series will be found to be the most suitable." Of these, the

most satisfactory metal salts will be those prepared from lithium, boron, calcium, magnesium, manganese, zinc, cadmium, iron, cobalt, nickel and lead. The most satisfactory compounds which we have employed are those prepared from zinc and cadmium. Among the salts which have proved to be particularly satisfactory are the halides such as the chlorides, chloroplatinates, bromides, and iodides; the nitrates, sulfates, phosphates, formates, acetates, propionates, benzoates, thiocyanates, boratesand like salts which are sufficiently soluble or fusible to permit the double salt to be formed. of these, the chlorides are generally preferred.

The term unsymmetrically substituted hydrazines means the free bases or derivatives there of which release the free bases to produce the complex compound. This term includes the N.N disubstituted hydrazines in which the twosubstituents are basically different as, for example, one being aromatic and the other aliphatic as well as the mono substituted hydrazines. The class of unsymmetrically substituted hydrazines may be represented by the formula pholyl, piperidyl and like groups.

The statement that x must be of a different class than R when R1 is hydrogemmeans that X must not be aryl when R is aryl and R1 and Y are hydrogens and that x must not be aliphatic when R is aliphatic and R1 and Y are hydrogens.

One valence of a doubly bonded carbon atom, as employed in the above definitions and in the claims, will be understood to include compounds inwhichboththexand theYvalencesare connected to the same carbon atom as in compounds represented by the formula and to include compounds in which the valence is of a carbon atom which is doubly bonded to some element other than carbon as in the compounds represented by the formulae By the expression an allryl, aralkyl or aryl nucleus, it will be understood that the indicated group is bonded to the nitrogen directly by means of a carbon atom of such nucleus. I Such nuclei may contain hydroxy, allroxy, nitro, halogen or amino substituents. Also, the term "alkyl" includes both saturated and unsaturated aliphatic radicals.

The hydrazines, which in general will be foimd to be most useful, are the mono-substituted and asymmetrical disubstituted hydrazines containing not more than one aryl group connected directly to the nitrogen or those hydro'zines in which one nitrogen forms part of a cyclic structure. Amongst the compounds which we have found to be most satisfactory are: Those prepared from:

1 mole ZnCiz and 2 moles phenyl hydrazine.

1 mole ZnCl: and 2 moles p-tolyl' hydrazine.

1 mole PbCh and 2 moles phenyl hydrazine.

1' mole zinc propionate and 2 moles phenyl hydrazine.

1 mole ZnCh and 2 moles penta methylene hydrazine.

1 mole CdCl: and 2 moles phenyl hydrazine.

These materials are employed by either milling them into the rubber or dusting the surface or spraying the surface of the rubber with a ,solution or suspension of the material. The softening action as hereinbefore pointed out begins at once, and continues over a period of time which depends upon the temperature and the composition of the rubber. With the zinc chloride and phenyl hydrazine addition product, the maximum softening will be reached in about 8 days at 25 C. or in about 20 hours at 70' C, The zinc chloride penta methylene hydrazine addition product will produce the maximum softening in about 4 hours at '70 C.-

"following example:

a,1sa,sos

Example i a One percent of'the hydrazine derivative milled into rubber with as little milling as possible-and the rubber was held at 70?.0. for 24 hours. The relative plasticity was ;determined,

by measuring'the thickness of a 2 cubic centiin thousandths oi' an inch.

satisfactory are; a

meter pelletafter being pressedbetween parallel .platesunder'aiload of-2 kg. for 5 minutesat'IO" C. The plasticity number is the char thickness 2 .Material 5 It has been round that thepresence of sulfur,

and of certain pigments such as carbonfblack exert a-retardingiaction on the rate of the softening of the rubber by means of. our compounds. When thesetingredients are present in the rubber mix, a longer ageing period and usually; 1

greater amount a of plasticizingagent is required.

-When'these agents are to be employedin the rubber, it will, in general, be preferred to treat 1 process the use of large amounts of the softening agentand long ageing periods be largely obviated.-

Other compounds which have proyed to, be

es phenyl I 1 mole 13% 3 mo 1 mole Li 2 mo ies phenyl l'mole ZnBr, 21mo es phenyl 1 mole ZnI, 2 mo es phenyl 1 mole CdBr, 2 mo les phenyl 1 molev CM, 2 mo es phenyl 1 mole ZnI, 5 moles phenyl 1 mole CnPtCl. 2 moles phenyl 1 mole N iCl, 2 moles phenyl 1 mole N iCl 5 moles pheny 1 mole M 2 moles pheny 1 mole CoCl. 2 moles pheny 1 mole C001. ,4 moles pheny 1 mole I Zn 010;, 3 moles phenyl 1 mole Cd(NO, I 3 moles phenyl 1 mole, Co(N0=)s 3 moles phenyl 1 mole 2x180 2 moles phenyl ,2 moles ZnSO 3 moles phenyl 1 mole- Zn(CH,COO), 2 moles phenyl 1 mole Zn(HCOO), 2 moles phenyl 1 mole Zn Benzoate 2 moles phenyl 1 mole Zn Furoate 2 moles phenyl 1 mole ZnCl, 2 moles o-tolyl 1 mole n i I ,2 moles m-tolyl 1 mole PbCl, 21110198 p-tolyl 1 mole CdClg 2 moles p-tolyl lmole Zn(CH.CQO), 2 moles p-toi l v 1 mole ZnCl, 7 2 moles a-nap thyl' hydrazine 1 mole ZnCl,' 2 moles b-naphthyl hydrazine 1 mole ZnCl, 1 mole phenyl ethyl hydrazine 1 mole ZnCl, 2 moles penta methylene hydrazine Other compounds may be prepared from'other hydrazines such as: phenylhydrazine, o-tolylhy-. drazine, asymmetrical diphenyl hydrazine, phenyl f dithio carbamic phenyl hydrazine (phenyl hydrazine C Sz reaction product), 'N,Nf b-oxy ethyl phenyl hydrazine, alpha naphthyl hydrazine; acetone phenyl hydrazone, asymmetrical dilauryl hy-' drazine, N,N phenyl benzyl hydrazine, mono acetyl phenyl-hydrazine, the thiourea resulting from the actionoi phenyl mustard oil on phenyl hydrazine, o-xenyl hydrazine, the reaction product of phenyl hydrazine and carbon dioxide,

' g the type formula phenyl hydrazlne reacted with sulfur dioxide,

are: asymmetrical di-tolyl hydrazines,asymmetrical di-xylyl hydrazines, asymmetrical di--biphenyl hydrazines, asymmetrical 'di-naphthyl hydrazines, asymmetrical phenyl ,vtolyl hydrazines, asymmetrical phenyl biphenyl hydrazines, asym- 'metrical phenyl naphthyl hydra-zines, asymmetri- I cal tolyl naphthyl hydrazines, asymmetrical dibenzyl hydrazine-asymmetrical phenyl benxyl hydrazinealasymmetrical di-hydroxyphen'yl hydrazines, i asymmetrical dl-chlorphenyl hydrazines, asymmetrical di-p-aminophenyl hydra- ,zines, asymmetrical phenyl phenol asymmetricaLtolyl phenol hydrazlnes, asymmetrical di-anisyl hydrazines, asymmetrical'phenyl t anlsyl hydrazines, asymmetrical "methyl phenyl hydrazines, mono xylyl hydr'azines, mono biphenyl hydrazlnes, mono-hydroxy phenyl hydrazines,

mono benzyl hydrazines, mono chlorphenyl hydrazines, mono aminopheuyl hydrazines, mono :anisyi hydrazines, mono methyl hydraaine's, mono lauryl hydrazines, dichl rphenyl hydraslnes, and phenyl l Among the metal-saltswhich be men-- 'tioned arenthe metallic salts of the following" acid reacting materials: hydrochloric which! driodic acid, hydrobromicvacid, acid,

boric acid, phenol, b-naphthol, cresols,

naphthol, xylenols. catechol, dihydr'oxy naphthalenes, dihydrox'ybiphenyls, formic acid, :furoic a'cid,stearic acid-oxalic acid, acetic acid, benzoic acid. phthalic acid, propionicacid'butyric acid,

oleic acid, palmitic acid, sulfonic acids, naphthoic acid-phenyl heme-acid, phenyl naphthoi'c acid, J

na'phthylbenzoic acid, n'aphthyl naphthoic acid, halogen substituted acids, chlor acetic acids (mono-, and dl-), anthranilic acids, anthracene.

phoric, acid chlorplatinic, acid, sulphur dioxide,

carbon dioxide, ethyl sulfonic acid, dithiocarbamic acid of phenyl hydrazine, dlthio'carbamic acid of, o-tolyl hydrazine, and other dlthiocarbamic acids. 1 I Q It will be apparent that a wide variety of hydrazines may be employed to produce complex organic compounds to be employed in accordance wlth our invention. Within the'limits of s defined hereinbefo're, the components R, R1

aminophenyl, chlornaphthyl, V-nitronaphthyl, a1- kylnaphthyl, biphenyl, alkylbiphenyl, chlorbiphenyl, nitrobiphenyl, amlnobiphenyl, cyclohexyl,

carboxylic acids,]nitric acid, sulfuric acid, 'phosphenyl, ethylphenyl, nitrophenyl; chlorphenyl,

\ known and described in the literature. A large I strued as broadly as number are described in Beilstein, Handbook der Organischen Chemie, vol. 4, 3rd edition, pages 653 and 654. Many other addition products can be formed by the methods described in this publication. Some of the addition products such as the phenyl or tolyl hydrazine zinc chloride'complexes will precipitate simply by shaking the hydrazine with a solution oi zinc chloride. Compounds may be obtained in a similar manner with a saturated solution or a slurry oi lead chloride and hydrazines. Some of the metal salts'comblue with the hydrazines in equal molecular proportions. Other metal salts react with large proportions .of the hydrazine in forming the complexes, according to the specific salts.

The complex organic compounds oi our'invem' tion are very effective plasticizing agents and are particularly desirable because they are stable to oxidation during storage and are high melting solids relatively insoluble in water." They are also relatively nontoxic. For these reasons, our compounds are more desirable for the purpose than the free hydrazines. For example, while phenyl hydrazine is a liquid which is quite volatile at milling temperatures, the zinc iodide addition product is a solid melting at PIS-180 .0. While phenyl hydrazine is readily oxidized in the air, the zinc chloride addition product is not oxidized by long exposure at 100 0.

While we have disclosed the preferred embodiments of our invention, it will be readily apparent to those skilled in the art that" many modifications and variations may be made therein without departing from the spirit of our invention. Accordingly, the scope or our invention is to be limited solely by the appended claimsconis permissible in view or the prior-art. 1 a 7 We claim: e 1. In the process of making articles or rubber,

the steps which comprise plasticizing" unvulcanized rubber by subjecting the rubber to the action oi a small amount or a complex organic compound, which is a chemical addition product of a metal -salt and an unsymmetrically substituted hydrazine, for asufllcient length of time tcproduce a substantial increase in the plasticity of the rubber.

2. In the process of making articles of rubber,

the steps which comprise plasticizing unvulcanized rubber by subjecting the rubber to the action of .a small amount of a complex organic compound, which 1 is a chemical addition. product of ametal saltand an unsymmetrically substituted hydrazine having at least one valence of at least one nitrogen oi the hydrazine nucleus satisfied by a hydrogen atom and having at least one valence of at least one nitrogen of the hydrazine nucleus satisfied by a carbon atom of an organic group, for a suiiicient length of time to produce a substantial increase in the plasticity oi the rubber. a

3. In the process of making articles of rubber, the steps which comprise 'plasticizin'g unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product or a salt of a metal betweenlithium' and lead in the electromotive series and an unsymmetrically substituted hydrazine having at least one valence characteristics the arsasos of at least one nitrogen of the hydrazine nucleus satisfied by a hydrogen atom and-having at least one valence oi at least on nitrogen 01' the hydrazine nucleus satisfied by a carbon atom of an zinc, cadmium, ferrous iron, cobalt, nickel and lead and an unsymmetrically substituted hydrazine having at least one valence of atleast one nitrogen oi the hydrazine nucleus satisfied by a.hydrogen atom and having at least one valence of at least one nitrogen or the hydrazine nucleus satisfied by a carbon atom of an organic group. for a suillcient length of time to produce a substantial increase in the plasticity oi the rubber.

5. In the process of making articles or rubber, the steps which comprise plasticizing unvulcanized rubber by subjecting the rubber to the action oi a small amount of a complex organic compound, which is a chemical addition product of a metal salt and an unsymmetrically substituted hydrazine containing at the most two substituent groups in which each of the substituent groups is an organic group having a carbon atom thereoi directlybonded to a nitrogen of the hydrazine nucleus all substituents being on only one nitro gen, for a 'suiilcient length oi time to produce a substantial increase in the plasticity of the rubber. I

6. In the process oi making articles of rubber, the steps which comprise plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition'product of a metal salt and a mono-substituted hydrazine in which the substituent is an organic group having a carbon atom thereof directly bonded toa nitrogen oi' the hydrazine nucleus, i'or a suilicient length of time to produce 'a substantial increase in the plasticity oi. the rubber. v

7. In the process or'making articles or rubber, the steps which comprise plasticizing imvulcanized rubberby subjecting the rubber to the action 01 a small amount oi' a complex organic compound, which is a chemical addition product oi a metal salt andan unsymmetrically substituted hydrazine'containing at the most two substituent an organic group having a carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus oneand only one of said carbon atoms being in an aromatic ring and all substituents being on only one nitrogen, for a suillcient length of time to produce a substantial increase in the plasticityorthe'rubber.

-18. Inthe process of making articles of rubber, the steps which comprise plasticizingunvuicanized rubber by subjecting the rubber to'the action of a small amount of a'complex organic compound, which is a chemical addition product of a metal salt and a mono-substituted hydrazine in which the substituentis an aromatic group having a ring carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus, for a suillcient length of time to produce a substantial increase in the plasticity oi'the rubber.

9. In the process of making articles of rubber,

the steps which comprise plasticizing unvulcanized rubber by subjecting therubber to the action of a small amount of a complex organic com-- pound which is a chemical addition product or a salt of .a metal selectedxfrom the group .of

' lithium, boron, calcium, magnesium, manganese,

zinc, cadmium, ferrous iron, cobalt, nickel and lead and an unsymmetrically substituted hydrazine containing at the most two substituent groups in which each of the substituent groups is an organic group having a carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus one and onlyone of said carbon atoms being in an aromaticgring and all substituents being on only one nitrogen, for a suiilcie'nt length of time to produce a substantial increase in the plasticity of the rubber. x r a 10. In the process of making articles of rubber, the steps which comprise plastlcizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic com pound, which is a chemical addition product of a salt of a metal selected from the group of lithium,

boron, 1 calcium, magnesium, manganese, zinc, cadmium, ferrous iron, cobalt,nickel and lead and 1a mono-substituted hydrazine in which the substituent is an aromatic group having a ring carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus, for a sumcient length of time to produce a substantial increase in the plasticity of the rubber.

ll. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action valence of atfleast one of a small amount of. a complex organic coma chemical addition product of ound, which is an unsymmetrically substituted a metal salt and hydrazine, for a suiilcient length of time to produce a substantial increase in the plasticity of the rubber. Y r

12. Unvulcanized rubber of increasedplasticity obtainableby subjecting the rubber to theaction of a small amount of a complex organic com pound, which is a chemical addition product of a metal salt and an unsymmetrically substituted hydrazinehaving at least one valeuceeoi at least one nitrogen of the hydrazine nucleus satisfied by a hydroger i atom and having at least one gen of the hydrazine nucleus satisfied by a hydro" gen atom and having at least one valence'oi at least one nitrogen of the hydrazine nucleus satisfled by a carbonlatom of an'organic group, fora sumcient length of time to produce a substantial I increase in the plasticity of the rubber.

o groups in which an organic group 4. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of a metal salt and an unsymmetrically substituted hydrazine, containing at the most two substituent each of the substituent groupsis having 'a carbon atom thereof "zinc, cadmium, nd an unsymmetrically substituted hydrazine containing'at the most two'substituent nitrogen of the hydrazine directly bonded to a nitrogen of the hydrazine nucleus all substituents being on only one nitrogen, for a su mcient length of time to produce a substantial increase in the plasticity of the rub ber.

of a small amount. of a'complea organic compound, which ls a chemical addition product of a metal salt and a mono-substituted hydrazine inwhich the substituent is an organic group hav ing-a carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus. tor a suillcient length of time to produce "a substantial increase in the plasticity of the rubber. L

16. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of a small amount. of a complex organic compound, which is a chemical addition product of axmetal salt and an unsymmetrically substituted hydrazine in which only one nitrogen carries substituents, such substituents being terminal carbon atoms of a cyclic'group' formingwith the nitrogen a heterocyclic ring, for a suiilcient length of time to produce a substantial increase in the plasticity of the rubber. j

17. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of .a small amount or a complex organic compound, which is a chemical addition produot' oi a salt-of a metalselected from the group of lithium, boron, calcium, magnesium, manganese, ferrous iron, cobalt, nickel and lead groups in which each of the substituent groups 'is an organic group having a carbon atom thereof directly bonded-to a nitrogen of the hydrazine nucleus one and only one of saidscarbon atoms being in an aromatic ring and all substituents being on only one nitrogen, for a suillcientien th of time-to produce a substantial increase, in the plasticity-of the rubber.

V Unvulcanized rubber of increased plasticity obtainable bysubiecting the rubber to the action 18. Unvulcanized rubber. of increased plasticity obtainable by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of a saltof a metal selected from the group of lithium, boron, calcium, magnesium, manganese, zinc, cadmium, ferrous iron, cobalt. nickel and lead anda mono-substituted hydrazine in which the substituent is an aromatic group having a ring carbon atom thereof directly bonded to a nitrogen I or the hydrazine nucleus, for a suilicient length oftime to produce a: substantial increase in the,

plasticity of the rubber..

19. In the process of making articles of rubber. the step which-comprises plasticizing unvulcanized rubber by subjecting the rubberto the action oi'a small amount oi a complex organic compound, which is a chemical additionproduct oi a chloride of a metal between lithium and lead in the electromotive series and anunsymmetrically substituted hydrazine havingat least one valence of at least one nitrogen of the hydrazine nucleus satisfied by a hydrogen, atom and in, which each substituent is an organic group joined to the nitrogen by means of a carbon atom, tor a .suihcient length of time to produce a'substantial increase in the plasticity of the rubber.;.

, 20. In the process of making articles ofrubber,

the step which comprisesplasticizing unvulcanized rubber by subjecting the rubber to the action of a small. amount of a complex organic compound, which is a chemical addition product of a chloride or a metal between lithium and lead in the electromotive series and an unsymmetrically substituted hydrazine in which only one nitrogen carries substituents, each substituent being an organic group joined to the nitrogen by means of a carbon atom, for a sumcient length of time to produce a substantial increase in the plasticity of the rubber.

21. In the process of making articles of rubber, the step which comprises plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of a chloride of a metal between lithium and lead in the electromotive series and a mono-substituted hydrazine in which the substituent is an aromatic group having a ring carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus, for a suflicient length of time to produce a substantial increase in the plasticit of the rubber.

22. In the process of making articles of rubber, the step which comprises plasticizing unv'ulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of a chloride of a metal between lithium and lead in the electromotive series and phenyl hydrazine, for a sufiicient length of time to produce a substantial increase in the plasticity of the rubber.

23. In the process of making articles of rubber, the steps which comprise plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of a metal salt and phenyl hydrazine, for a sufiicient length of time to produce a substantial increase in the plasticity of the rubber.

24. In the process of making articles of rubber, the step which comprises plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of one mole of the chloride of a divalent metal between lithium and lead in the electromotive series and two moles of an unsymmetrically substituted hydrazine in which only one nitrogen carries substituents,each substituent being an organic group joined to the nitrogen by means of a carbon atom, for a sufiicient length of time to produce a substantial increase in the plasticity of the rubber.

25. In the process of making articles of rubber,

the step which comprises plasticizing unvulcan-' ized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of one mole of the chloride of a divalent metal between lithium and lead in the electromotive series and two moles of a mono-substituted hydrazine in which the substituent is an aromatic group having'a ring carbon atom thereof directly bonded to a nitrogen of the hydrazine nucleus, for a sufficient length of time to produce a substantial increase in the plasticity of the rubbeit,

26. In the process of making articles of rubber, the step which comprises plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of one mole of the chloride of a divalent metal between lithium and lead in the electromotive series and two moles of phenyl hydrazine, for a sufllcient length of time to produce a substantial increase in the plasticity of the rubber.

2'7. In the process of making articles of rubber, the step which comprises plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of one mole of zinc chloride and two moles of an unsymmetrically substituted hydrazine having at least one valence of at least one nitrogen of the hydrazine nucleus satisfied by a hydrogen atom and in which each substituent is an organic group joined to the nitrogen by means of a carbon atom, for a sumcient length of time to produce a substantial increase in the plasticity of the rubber.

28. In the process of making articles of rubber, the step which comprises plasticizing'unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product oi. one mole of zinc chloride and two moles of phenyl hydrazine, for a sumcient length of time to produce a substantial increase in the plasticity of the rubber.

29. In the process of making articles of rubber, the step which comprises plasticizing unvulcanized rubber by subjecting the rubber to the action of a small amount of a complex organic com-,

pound, which is a chemical addition product of one mole of cadmium'chloride and two moles of, phenyl hydrazine, for a sufilcient length of time to produce a substantial increase in the plasticity of the rubber.

30. In the process of making articles 01' rubber,

the step which comprises plasticizing unvulcanpound, which is a chemical addition product oi.

a chloride of a metal between lithium and lead in the electromotive series and an unsymmetrically substituted hydrazine having at least'one valence of at least one nitrogen of'the hydrazine I nucleus satisfied by a hydrogen atom and in which each substituent is an organic group joined to the nitrogen by means of a carbon atom, for a sufiicient length of timeto produce a substantial increase in the plasticity of the rubber.

32. Unvulcanized rubber of increased plasticity obtainable by subjecting the'rubbe r'to the action of a small amount of a complex; organic compound, which is a chemical additionproduct of a chloride of a. metal between lithium and lead in the electromotive series and s'an unsymmotrically substituted hydrazine in which only one nitrogen carriesxsubstituents, each substituent being an organic group joined to the nitrogen by means of a carbon atom, for a sufflcient length of time to produce a substantial increase in the plasticity of the rubber,

33. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of a small amount or a complex organic compound, which is a chemical additionproduct of a chloride of a metal between lithium and lead in the electromotive series and phenyl hydrazine,

' a metal salt and phenyl hydrazine, for a sufllcient length or time to produce a substantial increase;

in the plasticity of the rubber. H

35. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of a small amount of a complex organic compound, which is a chemical addition product of one mole of the chloride of a divalent metal between lithium andilead in the electromotive series and two moles ofan'unsymmetrically substituted hydrazine in which only. one nitrogen carries substituents, each substituent being an organic group joined to the nitrogen by means oi. a carbon atom, for a sufilcient length-o1 time to produce a substantial increase in the plasticity of the rubber.

36. Unculcanized rubber or increasedplasticity obtainable by subjecting the rubber to the actionof a small amount of a complex organic compound, which is a chemical addition product or one mole of zinc chloride and two moles'of phenyl hydrazine, for a sufllcient length of time to produce a substantial increase in the plasticity of the rubber., 1 v

37. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action 01 a small amount or a complex organic coma pound, which is a chemical addition product 01' one mole of cadmium chlorideand two moles of phenyl hydrazine, tor a suflicient length oi! time to produce a substantial increase in the plasticity of the rubber. v

38. Unvulcanized rubber of increased plasticity obtainable by subjecting the rubber to the action of a small amount of a complex organic compound, which'is a chemical addition product of one mole of lead chloride and two moles of phenyl hydrazine, for a sufllcient length oi. time to produce a substantial increase in the plasticity of the rubber.

IRA WILLIAMS.

CARROLL CUMMINGS SMITH. 

